Canon 70-300 mm IS USM blurry photos

[kpsanghvi]

Recently I bought a new  70 - 300 Canon IS (not the L white one). I was clicking famingoes and  other waders. Used servo focus and one shot in aperture priority mode with a wide aperture. I was not too impressed by its sharpness especially at 300. The sharpness I get with my 18-135 STM is much better compared to the 300 especially when cropped . Since the investment is already made and I cannot exchange it also for another lens what is the best way out. How do I improve sharpness. At what tele does it give the best sharpness. Should I send it for a check. It is under warranty. What would be the best option if I were to sell it buy another one.

After I had problems I read on the net that the sharpness of this lens isn't good at all. I am wondering why does Canon still sell it or does not do something about it. Does not it have a reputation to save.

[kpsanghvi]

Have posted 3 test photos. Would need your expert opinion about lens sharpness. 

Regards and thanks a ton

[RobertTheFat]

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@kpsanghvi wrote:

Have posted 3 test photos. Would need your expert opinion about lens sharpness. 

Regards and thanks a ton

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Given that they're displayed at Web resoluion, I don't see how those pictures could have been improved. All the blurriness that I can see appears due to depth-of-field limitations.

[ebiggs1]

I totally agree with Robert.  They look like what is to be expected from that lens.

[kpsanghvi]

Thanks a ton. It is a big relief that the lens is normal but what would I like to know is that how does one differentiate between blurriness due to lens or hand shake or depth of field.

[ebiggs1 · Accepted solution]

First off nobody gets every photo absolutely right.  Have you heard the common phrase "I get more keepers that way."?

The reason that phrase exists is, some pictures despite our best efforts don't turn out as we wanted.

It could be the limit of the lens or camera.  And yes even you.  I confess it happens even to me! 

Fact is a 300mm lens that is rather slow, is very dim light and on a light body can be a challenge to get all perfect. It will take time and practice. You need to be lucky, too.  However the more you practice the luckier you will be.  Make sense?

Remember with the crop factor figured in, you are dealing with nearly 500mm of telephoto.  That is equivalent to a 10x power telescope or binoculars. Problem is all the issues are also magnified 10 times.

Go out and use your gear.  Expect some to not turn out as you thought.  But hopefully more and more will as you learn.  The samples you displayed are not bad at all.

[RobertTheFat · Accepted solution]

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@kpsanghvi wrote:
Thanks a ton. It is a big relief that the lens is normal but what would I like to know is that how does one differentiate between blurriness due to lens or hand shake or depth of field.

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If part of the picture (i.e. everything within a fairly narrow range of distances) is in focus and the rest isn't, the problem is shallow depth of field. If the camera shakes, everything will be blurry.

[kpsanghvi]

Thanksa ton Waddizzle, ebiggs1 and Bob for enlightening me and that too with absolute alacrity and promptness.

[TomDibble · Accepted solution]

I have the older model (I assume you have the 70-300 IS II, as you have bought it recently; mine was bought a few years before the ii came out).

I have found that the tricks to getting sharp photos with this lens are:

1. NEVER shoot fully zoomed-out. Try somewhere in the 225-250mm range, which is just "full zoom out, then nudge it barely back". I get much more reliably sharp images at this range, and a crop of this zoom range to the same size image as the 300mm has better detail resolution.

2. Never shoot "wide open" if sharpness is more important than shallow DoF. The best aperture, per FoCal, is around 11-13 when zoomed in to the 225-300 range. Zoomed out f/8 is sharpest. These aren't going to give any good "bokeh" results, but they will yield better sharpness at the focal plane.

3. Calibrate the AFMA if possible with your camera. Amongst all my lenses, the 70-300 is by far the one most in need of autofocus microadjustment, primarily at the "long" end. It isn't a huge deal, but your copy may be in need of some adjustment. I highly recommend Reikan's FoCal product for this, as it is highly automated and yields consistent results (well, as consistent as your lens' autofocus is ... my 50mm 1.8 has horribly inconsistent autofocus and, predictably, yields differing AFMA values every time I test it).

Overall, treat the 70-300 as a 70-200 with just a shade more reach and a min aperture of f/8 (and not-nearly-as-sharp glass and not-nearly-as-high price accordingly). Staying in that range gives me nice, consistent results. I always notice it when I step out of it.

[kpsanghvi]

Thanks Tom. Will try not to use extremes of focal length and wide apertures

[ebiggs1]

Tomdibble has hit on some common know issues with any lens.  Rarely is any lens at its best wide open, low f-stop number.  And most zoom lenses are not at there best at either end fully zoomed or contracted.  This does not mean you should not use either of these.  Just beware of the physical limits of the design.